I think with our small wheels a speed drive combined with a smaller chainring will give you all the lower gears while it will increase the top speeds a little bit as well.

with the mountain drive you gonna spin like crazy ...

thor

Even climbing a 12% grade pulling a trailer? I did Mt Ventoux pulling BOB and I would have enjoyed a lower gear on the last six kilometers. I was thinking more of using the mountain gear as a bail out when I needed some more spin action. I'm not really into heavy pedal pumping, but I also haven't tried out 20'' wheels yet so maybe they are a lot different, and perhaps a smaller front chain ring would be the ticket. Thanks!

If you haven't got 20" wheels what bike was it that you used to tow your BoB up that darn mountain?
I would second Thor's thoughts, often the problem with folders is getting higher gears without a too tiny rear cog.